An inpatient program with selected overnight stays, for childhood and adolescent neuropsychiatric disorders is ongoing. The conditions currently under study are hyperactive children (HAC) and Gilles de la Tourette's Syndrome. Pharmacological compounds under study in these disorders include methylphenidate, amphetamine, piribedil, L-dopa, and tryptophan. Pharmacokinetic studies with clinical responses are ongoing. Central neurotransmitters and their metabolites are being studied in plasma and urine. Amphetamine half-life in children is about one-third that of adults. Behavior and motor activity response do not correlate with plasma amphetamine levels. These responses occur during the absorption phase as determined by serial plasma amphetamine following a single dose. Urinary 3-methoxy-4-hydroxy-phenyl glycol shows a time-related decrease during treatment with d-amphetamine; homovanillic acid is unchanged. Piribedil is safe, but clinically ineffective in HAC.